Vibrations, surges and noise developed in mechanical springs in a railway car are generally transmitted to the car body. This causes passenger discomfort.
The vibrations, surges, and noise result from a number of operation conditions. For example, mechanical springs may have natural frequencies at which they tend to vibrate. Sudden impacts transmitted from the tracks may cause surges and noise in the springs, which in turn are transmitted to the car body.
Different types of damping elements have been used in connection with mechanical springs. Generally, these have been located at the top and bottom of the springs. Such arrangements have not been entirely successful in railway car applications, especially where double spring arrangements are used when one spring is disposed inside the other with some space therebetween.
Some patents relating to spring damping include U.S. Pat. Nos. 3,795,390; 3,977,700; 3,762,694; 2,660,423; 2,822,165 and 3,206,184.